as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Example Sentences
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Recent Examples of insidious
What makes this deal particularly insidious is the trade-off at its core.
—
Joe Wilkins, Futurism, 10 June 2026
But most of its failures are subtler, more insidious.
—Katy Waldman, New Yorker, 10 June 2026
But there is an insidious quality.
—Rory McDonald, Fortune, 6 June 2026
Best known for comedy series like Community (2009-15) and GLOW (2017-19), Alison Brie is taking on the role of Evil-Lyn, an insidious enchantress who serves as Skeletor’s main accomplice.
—Keith Langston, PEOPLE, 6 June 2026
See All Example Sentences for insidious
Joe Wilkins, Futurism, 10 June 2026
But most of its failures are subtler, more insidious.
—Katy Waldman, New Yorker, 10 June 2026
But there is an insidious quality.
—Rory McDonald, Fortune, 6 June 2026
Best known for comedy series like Community (2009-15) and GLOW (2017-19), Alison Brie is taking on the role of Evil-Lyn, an insidious enchantress who serves as Skeletor’s main accomplice.
—Keith Langston, PEOPLE, 6 June 2026
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
-
The terrain can be treacherous, but the guide offered patience and grace for our entire group, slowing down without comment when someone was straggling and prioritizing water breaks.—
Condé Nast,
Condé Nast Traveler,
17 June 2026
-
Shinnecock’s fairways create optical illusions off the tee, the bunkering is treacherous and the greens are, in some places, designed to repel the ball from the putting surfaces.—
Gabby Herzig,
New York Times,
16 June 2026
Adjective
-
Star power takes a neutral cat-eye base and turns it into a subtle statement moment.—
Amanda Le,
InStyle,
17 June 2026
-
Where their Florida style is bold and flamboyant, the ranch is subtle and defined by a rich, earthy palette.—
Elizabeth Kiefer,
Architectural Digest,
17 June 2026
Adjective
-
According to the department, at the time of the chase, Buban had multiple outstanding arrest warrants against him, including for being a felon in possession of a firearm, taking a vehicle without consent, false impersonation and petty theft.—
Kassia Bonesteel,
CBS News,
19 June 2026
-
According to Peña, a producer relayed the false information to her through an earpiece during a live broadcast.—
Nicole Acevedo,
NBC news,
19 June 2026
Adjective
-
The suit alleges the group, known widely as WPATH, made deceptive claims about gender-affirming care for minors and that its members profited off the claims.—
ABC News,
ABC News,
17 June 2026
-
Grand Canyon’s rim-to-river routes can be deceptive because the steepest physical test comes on the way out, after hikers have descended into hotter terrain, experts say.—
Jessica Mekles,
FOXNews.com,
15 June 2026
Adjective
-
This is perhaps the most perfidious practice of this sort of politics.—
David M. Drucker,
Twin Cities,
3 June 2026
-
Pakistan was a perfidious ‘ally’ in Afghanistan, backing the Taliban while pretending to be our friends.—
Efrat Lachter,
FOXNews.com,
18 Apr. 2026
Adjective
-
The researchers calculated welfare losses from incorrect beliefs could potentially reach up to 43% of the initial loan balance in the most extreme cases, translating to roughly $21,500 on the median borrower’s $50,000 in debt.—
Catherina Gioino,
Fortune,
17 June 2026
-
For example, many borrowers are getting incorrect estimates of what their bill would be on IBR, Rodriguez said.—
Annie Nova,
CNBC,
16 June 2026
Adjective
-
Tom Kim dropped two shots at the wrong time and shot 72.—
Doug Ferguson,
Los Angeles Times,
21 June 2026
-
Every traveler has a trip that went spectacularly wrong.—
Josh Rivera,
USA Today,
21 June 2026
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 23 Jun. 2026.
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